The California state legislature passed a bill Thursday approving $24 million to expedite the confiscation of the estimated 40,000 handguns and assault weapons illegally owned by Californians.

SB 140, authored by Sen. Mark Leno (D-San Francisco), seeks to remedy the gun-confiscation backlog that has left thousands of illegal guns on the streets, including those owned by those with criminal convictions or serious mental illness.

“We are fortunate in California to have the first and only system in the nation that tracks and identifies individuals who at one time made legal purchases of firearms but are now barred from possessing them,” Leno said in a statement.

“However, due to a lack of resources, only a few of these illegally possessed weapons have been confiscated, and the mountain of firearms continues to grow each day."

The measure will take $24 million from the Dealer Record of Sale (DROS) surplus funds and give it to the California Department of Justice, which is in charge of confiscating illegal guns. The DROS account holds fees that are imposed upon every transfer or sale of a firearm in California.

Assemblyman Brian Jones (R-Santee) said he voted against the measure because the fees that make up the DROS funds are intended to cover the cost of background checks -- not confiscations.

"For example, if you go to the DMV and pay for a driver's license, that fee is for processing the driver's license, not for setting up sting operations for catching drunk drivers," he said.

"If the legislature wants to raise extra funds for the DOJ, it would have to impose a tax on firearm sales, which requires a two-thirds vote," he added.

Brandon Combs, executive director of the gun advocacy group Calguns Foundation, agrees that gun confiscation should be paid for out of the state's general fund. His and other pro-gun groups have argued that California's fees on gun buyers are exorbitant.

"The state should not be stealing millions of dollars from gun owners who were overcharged," Combs said.

Assemblyman Tim Donnelly (R-Twin Peaks) told the Los Angeles Times that he voted against the measure because it is “a dangerous practice” to “send SWAT teams into our neighborhoods” to collect the firearms.

The funds will go toward enforcing the California DOJ's Armed Prohibited Persons System (APPS) program, which began in 2007. APPS cross-references various databases to check people who have legally purchased handguns and registered assault weapons since 1996 against individuals who are prohibited from owning or possessing firearms.

APPS also cross-references gun owners with individuals who have reported to the state DOJ as mentally ill. Doctors and hospitals are required to report to the state individuals who were found to be a danger to themselves or others, or who were certified for intensive treatment for a mental disorder.

Lynda Gledhill, spokesperson for the California DOJ, said that of the individuals deemed unfit to own guns, about 30 percent have a criminal record, 30 percent are mentally ill, 20 percent have a restraining order out on them and a small percentage have a warrant out for their arrest.

California is the only U.S. state where law enforcement officials confiscate guns from the homes of individuals not legally permitted to own them. Because gun-confiscating agents do not obtain search warrants, their job involves convincing people to let them into their homes and hand over their guns. If an individual does turn over a gun, he or she can be arrested on suspicion of illegally owning a firearm.

Over the past five years, agents conducting twice-weekly sweeps have confiscated more than 10,000 guns. Using the $24 million from SB 140, the California DOJ says it would take three years to catch up with the backlog of confiscated illegal guns.

Leno's bill returns to the Senate for approval of some noncontroversial amendments before heading to Gov. Jerry Brown’s (D) desk. If SB 140 is signed by the governor, it would take effect immediately.

"This makes enormous sense and is one of the only ways available to reduce access to already purchased firearms," Deborah Azrael, associate director of the Harvard Youth Violence Prevention Center. "Universal background checks, as much as we should have them, can affect only the next gun purchased, not the sizable reservoir of guns already out there."

Adam Winker, UCLA law professor and expert on constitutional law, commented on the passage of the California bill after the U.S. Congress' failure to enact national gun background checks.

"We're likely to see much more activity at the state level in the wake of Congress's failure to act," Winkler said. "The gun-control movement's best options now are gun-control laws at the state."